Try not to provoke the Peruvian green velvet tarantula, because when it bites, it leaves a red swelling that hurts like a beesting. But even if you do have an unfortunate run-in with the spider, take solace in this: Scientists are at work turning its venom into sweet relief from your suffering.

Ever since researchers identified painkilling peptides in the tarantula's venom, labs around the world have been working to fine-tune them into drugs safe for humans. These molecules target the cell membranes of neurons, blocking receptors there that channel messages through the body. The trick is to shut down the right receptors without stopping others from letting important nerve signals get through.

"Tarantulas produce this cocktail of several toxins to kill prey quickly, so it targets several channels—muscles, breathing—to paralyze and kill," said Sónia Troeira Henriques, senior research officer at the University of Queensland's Institute for Molecular Bioscience. "Some are very targeted. The idea is to choose channels that are responsible for pain but not, for example, cardiac movement."

The researchers identified a suitable peptide, then watched how it worked when it reached the cell membrane. "We found that it first needs to bond, then have the right orientation, and then act on the receptor," said Henriques. They studied its structure, then designed a synthetic version of their own that was even more likely to hit the pain channel over all others.

If it works, the researchers could be on track to a new drug that would be an alternative to the opioids currently on the market. "It's easy to develop resistance or side effects with opioids," said Henriques. "The idea is to increase the pool of drugs available."